Column count doesn't match after doing alias

[Rushikesh_Dikey]

Hi Team,

I am trying to merge two different index, so i used

// POST /_aliases
{
  "actions": [
    { "add": {
        "index": "abc",
        "alias": "poc"
      }
    },
    { "add": {
        "index": "xyz",
        "alias": "poc"
      }
    }
  ]
}

but after doing it i and getting lesser column in target index.
abc has 277 fields
xyz has 197 fields
and in target poc i am getting 342 fields only where i should get 474 fields.

[Rushikesh_Dikey]

even i tried downloading CSV of the combined index, which has data from only one of the index!